1. Field of the Invention
The present invention relates to a printing apparatus and a carriage scan driving method. More particularly, the invention relates to a serial type printing apparatus and a carriage scan driving method scanning a carriage in a direction perpendicular to a feeding direction of a printing medium.
2. Description of the Related Art
It is typical to gradually complete printing over an entire area of a printing medium by repeating a printing operation, in which printing is performed by scanning the carriage and performing printing by means of a printing head mounted on the carriage, and a feeding operation in which a printing medium is fed for a predetermined amount in a direction perpendicular to the scanning direction of the carriage.
Such serial type printing apparatus is controlled by scanning of the carriage so that a scanning distance of the carriage becomes the shortest, depending upon a printing region, in order to shorten a printing period.
Also, the carriage varies speed during an acceleration stage, constant speed stage, and deceleration stage during one scan, to perform printing at a constant speed condition and not to perform printing during the acceleration and deceleration stages. Therefore, it has been proposed to shorten the printing period by performing feeding of the printing medium during the acceleration and deceleration stages. For example, Japanese Patent Application Laid-Open No. 1-101173 (1989) has proposed a method to control an acceleration start timing of the carriage depending upon a period required for the feeding operation of the printing medium in order to certainly complete feeding of the printing medium by the completion of acceleration of the carriage.
However, printing regions are not always the same per line and can be long in one line and short in another. In the conventional method, a difference of the printing position due to a difference of the printing regions per line is not taken into account in scan-controlling of the carriage. Thus, the same control is applied for any lines, and whereby shortening of the printing period depending upon the difference of the printing region cannot be expected.
On the other hand, in the printing apparatus of an ink-jet printing system, it is required a certain period from ejection of an ink to hitting on the printing medium. Thus, the printing apparatus is required to effect correction of arrival time to the printing medium from ejection of the ink when scanning a carriage. Therefore, the printing apparatus can not shorten a printing period corresponding to that scanning period.
Furthermore, the ink jet-printing apparatus regularly performs a recovery operation even during a printing operation for the purpose of removing ink of increased viscosity by an ejecting operation for a plurality of times. However, in the conventional method, scan controlling of the carriage has not been performed when taking the period required for the recovery process into account to perform the same scan controlling in both the scan performing recovery operation and the scan not-performing recovery operation.
On the other hand, in not only the printing apparatus of the ink-jet printing system but also various bidirectional printing apparatuses in which the scanning direction of the carriage is different per line, namely the printing operation is performed in both the forward scan and the reverse scan, and it is required to make correction for deviation due to a scanning play of the carriage and a phase delay of the motor, or the like, by scan of the carriage. The shortening of the printing period cannot be achieved for the period required for correction as set forth above.
The present invention has been worked out in view of the problem set forth above. It is an object of the present invention to provide a printing apparatus and a carriage scan driving method in which printing can be performed in a shorter period per printing pattern.
A printing apparatus of the present invention scans a carriage mounting a printing head over a printing medium a plurality of times, to perform printing upon respective scan and to perform feeding the printing medium for a predetermined amount in a direction different from a scanning direction of said carriage between scans of plurality of times for printing on a printing medium. The printing apparatus includes means for getting information relating to a printing medium feeding period required for feeding the printing medium for the predetermined amount after completion of printing in a preceding line in a preceding scan. The printing apparatus also includes means for setting a carriage scanning period required to start printing of the next line after completion of printing in said preceding line so as to be substantially equal to the printing medium feeding period depending upon the printing completion position of the preceding line and the printing start position of the next line. The printing apparatus further includes means for driving said carriage to scan depending upon a period set by said carriage scanning period setting means.
By such construction of the present invention, the carriage scanning period is set depending upon the printing completion position of the preceding line and the printing start position of the next line, which are different per printing pattern, and the carriage driving means drives the scanning of the carriage so that the scanning of carriage from the printing start position of the next line after completion of printing of the preceding line, and feeding of the printing medium in the predetermined amount, are completed simultaneously. Therefore, printing can be performed at a possible minimum period, depending on the respective printing pattern.
The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.